A least-voltage drop high output resistance current source for neural stimulation

This paper presents a feedback technique to increase the output resistance of a MOS current mirror circuit that requires only one effective drain-source voltage drop. The proposed circuit requires a few additional current braches to form two feedback loops. With its compact structure, the proposed circuit is suitable as a current generator for neural stimulation. Simulation results, using 0.35 μm AMIS I3T25 technology, show that the proposed current generator, applied for bi-phasic stimulation, can convey more charge to a series resistive-capacitive load compared to the widely use low-voltage cascode current source.